This invention relates generally to solid-state electronic watches, and more particularly to a watch assembly in which time display and integrated circuit modules are interlinked by a flexible circuit board which also connects the circuit module to power cells and other discrete elements of the assembly.
The term solid state electronic timepiece or watch, as used herein, is limited to devices provided with an electro-optic time display and having no moving parts. The traditional, spring-powered mechanical watch produces rotary motion for driving gear works that operate the moving hands or time indicators. In those electronic watches which also have a moving hand read-out, the oscillations of a balance wheel or the vibrations of a tuning fork are electronically-sustained. These oscillations or vibrations are converted into rotary motion for driving the gear train; hence such electronic timpieces are not designated solid state watches.
However, in more recently-introduced types of electronic watches such as those disclosed in U.S. Pat. Nos. 3,756,103 and 3,759,031, electrical pulses derived from a crystal-controlled time base serve to actuate a multi-digit electro-optic display formed either by light-emitting diodes (LED) or by liquid-crystal elements (LCD), no moving parts being entailed. In such solid-state watches, the high-frequency output of the time base is fed to a frequency converter constituted by a chain of divider stages. The output of the converter, consisting of low-frequency timing pulses, is applied to a display actuator in the form of a miniature time-computer module that counts the input pulse train, encodes it in binary form and then decodes and processes the results to provide the appropriate activating signals at the display stations.
The power requirements of an LED display are relatively high, and should the display be continuous, the life of the miniature battery would be brief. It is for this reason that commercially-available types of solid-state watches having LED displays are provided with a normally-quiescent display. The display is turned on only when the user depresses a push-button demand switch, thereby conserving power and prolonging the life of the battery. In one such watch, the display is programmed so that upon merely touching the push-button switch, the minutes and hours are indicated for an interval of one and one-quarter seconds, whereas continued depression of the switch causes the minutes and hour data to fade and the seconds to appear and to continue to count as long as the button is held in. In this arrangement, precise computation of time is continuous and independent of whether or not it is displayed, so that the moment the switch is depressed, timing signals are applied to the display. U.S. Pat. Nos. 3,560,990; 3,576,099 and 3,664,118 disclose electronic watches of this type.
Of particular interest in the context of the present invention is U.S. Pat. No. 3,803,827, whose disclosure is incorporated herein by reference. In the solid state watch disclosed in this patent, a crystal-controlled oscillator is coupled through an integrated-circuit frequency divider and display actuator to an LED display. Fitted within the wristwatch case is a one-piece frame which houses the entire wristwatch assembly, including a pair of power cells and an oscillator trimmer capacitor. Ready access may be had to these cells and the trimmer by removal of the watch case back.
While the modular solid state watch construction disclosed in U.S. Pat. No. 3,803,827 facilitates the assembly, adjustment and repair of the movement, and makes it easier to replace the batteries, a large number of leads and other discrete conductors are required to effect connections to terminals of the display package containing the light-emitting diodes forming the display stations and to effect connections to the terminals of the integrated circuit. Thus in putting together a solid state watch of the type disclosed in this patent, it is not simply a matter of fitting modules together within a case, for an elaborate hook-up procedure is involved which adds substantially to the cost of producing such watches.